Nonpoint source pollution poses as many problems as point source pollution by adding bacteria, nutrients, sediment, pesticides, and toxic materials to the Sound.With the increase of population in New York and Connecticut and the building of superhighways, which added more pollutants to the waterways leading to several beach closings during the summer. The Long Island Sound is a cesspool of many contaminants including heavy metals such as lead, copper, and mercury leading to bioaccumulation in organisms. Bioaccumulation occurs when fish ingest these heavy metals. Other organisms that digest these fish accumulate these heavy metals and the more digestion leads to more and more metals in the tissues of these organisms. The overpopulation and urbanization of this estuary leads to eutrophication. Eutrophication is the process by which there is a buildup of organic matter in an ecosystem. This can lead to the death of a lake or pond.
Construction of houses, buildings, and the paving of streets increases stormwater runoff which does not have the benefit of the natural filtration process associated with the absorption of precipitation through soil leading to groundwater aquifers. Stormwater runoff picks up trash, oil from cars, sediments, and other pollutants that are piped directly to rivers and eventually to the Sound.
Atmospheric deposition is another source of nonpoint source pollution to the Long Island Sound, This comes from pollutants in the air that fall to the Sound when it precipitates. When factories were built, an attempt to keep air pollution from being at ground level by building smoke stacks. Little did they know that the smoke would travel up into the atmosphere and would make its way back down to the surface of the land, rivers and the Long Island Sound? This is another example of nonpoint source pollution.
Floatables are another form of pollutant that affects the Long Island Sound. This term refers to water-borne debris in the form of plastics, paper, cigarette filters, and other material. These floatables have killed numerous seabirds and other animals that live in the sea.
Pathogens are another pollutant that plagues the Long Island Sound. These are microorganisms that can cause diseases such as diarrhea, dysentery, cholera, typhoid fever, and hepatitis. Pathogens find their way to the Sound through sewage treatment plants, malfunctioning septic tanks, sewer overflow, and runoff from animal wastes.
Then there are organic substances, which means a substance containing carbon and hydrogen.These substances are produced naturally by plants and animals, but are also synthetically manufactured as in the case of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Pesticides can be either naturally produced or synthetically produced. PCBs and certain pesticides such as DDT have been banned because of its major health risks such as the risk of causing cancer and birth defects.